PRACTICE XVIII 



DETERMINATION OF CONDUCTIVITY OF HEAT IN SOILS 



The five regular stock soils are used. 



In one end of the tray place the copper vessel for the water and 

 put asbestos board on all sides except the one in contact with 

 the soil. Place the same quantity of water in each copper vessel. 

 Fill the trays with soil. Place thermometers, which read uni- 

 formly, with the bulb at a depth of 2^ inches and 1, 2, 3, 4, 5, 

 and 6 inches from the vessel of water. Heat the water with a 

 Bunsen burner through the opening in the bottom of the tray. 

 Remove the burner when the water reaches a temperature of 

 95° C. and record the temperature of the soil. Record the tem- 

 perature reached at the end of each five- or ten-minute period 

 for about an hour. 



Students may work in sets of five, each taking the tempera- 

 ture in one soil and exchanging with each of the other four for 

 comparison. 



Is there any relation between porosity and conductivity ? 



References. 



" Soils," Lyon and Fippin, pp. 459-460. 



" Physical Properties of Soil," Warington, pp. 168-174. 



Fig. 6. Apparatus for determining Conductivity of Heat 



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